Low-power and lossy networks (LLNs), e.g., sensor networks, have a myriad of applications, such as Smart Grid and Smart Cities. Various challenges are presented with LLNs, such as lossy links, low bandwidth, battery operation, low memory and/or processing capability, etc. One of the keys in managing the multitude of LLN devices is the ability to effectively poll the devices for their liveness, e.g., whether the device is engaged in network activity. For example, when supporting managed services, e.g., remote infrastructure management (RIM), the end user requires that the status of each device is accurately detected. Problematically, the “state polling” approach, whereby a network management system (NMS) retrieves state information from a device using a protocol such as Simple Network Management Protocol (SNMP), or even a lighter protocol such as Constrained Application Protocol (CoAP), consumes excessive amounts of bandwidth, and thus is not ideal for implementation in LLNs. Furthermore, implicitly detecting network activity via traffic observation, e.g., by using Deep Packet Inspection (DPI) on traffic sent through a Field Area Router (FAR), may not be possible with “quiet” devices.
It should be understood that the above-referenced drawings are not necessarily to scale, presenting a somewhat simplified representation of various preferred features illustrative of the basic principles of the disclosure. The specific design features of the present disclosure, including, for example, specific dimensions, orientations, locations, and shapes, will be determined in part by the particular intended application and use environment.